A Functional CT Contrast Agent for In Vivo Imaging of Tumor Hypoxia

Nanogold-albumin conjugates: transformative approaches for next-generation cancer therapy and diagnostics

Nanogold-albumin conjugates have garnered significant attention as a highly adaptable theranostic platform, capable of delivering a wide range of therapeutics, from small-molecule drugs to larger biomolecules, while offering promising applications for monitoring and managing cancer. The remarkable theranostic capabilities of these conjugates stem from the combined strengths of gold and albumin, which provide low toxicity, a large surface area, customizable surface chemistry, and unique optical properties, all contributing to their potential in cancer therapy. This review delves into the design and development of two primary types of nanogold-albumin conjugate: supramolecular albumin-coated gold nanoparticles (GNP-BSA/HSA) and albumin-templated ultra-small gold nanoclusters (GNC-BSA/HSA). Each strategy offers distinct advantages, enabling the fine-tuning of conjugate properties to optimize therapeutic delivery and facilitate cancer-specific bio-sensing. The integration of gold and albumin further improves biocompatibility, extends circulation time, and enhances tumor targeting, making these conjugates an attractive option for cancer treatment. The review also focuses on the refinement of surface chemistry to achieve precise targeting of cancer cells, as well as the challenges and future prospects for advancing nanogold-albumin systems in clinical applications.

Engineering Stimuli-Responsive Materials for Precision Medicine

Over the past decade, precision medicine has garnered increasing attention, making significant strides in discovering new therapeutic drugs and mechanisms, resulting in notable achievements in symptom alleviation, pain reduction, and extended survival rates. However, the limited target specificity of primary drugs and inter-individual differences have often necessitated high-dosage strategies, leading to challenges such as restricted deep tissue penetration rates and systemic side effects. Material science advancements present a promising avenue for these issues. By leveraging the distinct internal features of diseased regions and the application of specific external stimuli, responsive materials can be tailored to achieve targeted delivery, controllable release, and specific biochemical reactions. This review aims to highlight the latest advancements in stimuli-responsive materials and their potential in precision medicine. Initially, we introduce disease-related internal stimuli and capable external stimuli, elucidating the reaction principles of responsive functional groups. Subsequently, we provide a detailed analysis of representative pre-clinical achievements of stimuli responsive materials across various clinical applications, including enhancements in the treatment of cancers, injury diseases, inflammatory diseases, infection diseases, and high-throughput microfluidic biosensors. Finally, we discuss some clinical challenges, such as off-target effects, long-term impacts of nano-materials, potential ethical concerns, and offer insights into future perspectives of stimuli-responsive materials.

A Contrast-Enhanced Tri-Modal MRI Technique for High-Performance Hypoxia Imaging of Breast Cancer

Personalized radiotherapy strategies enabled by the construction of hypoxia-guided biological target volumes (BTVs) can overcome hypoxia-induced radioresistance by delivering high-dose radiotherapy to targeted hypoxic areas of the tumor. However, the construction of hypoxia-guided BTVs is difficult owing to lack of precise visualization of hypoxic areas. This study synthesizes a hypoxia-responsive T1, T2, T2 mapping tri-modal MRI molecular nanoprobe (SPION@ND) and provides precise imaging of hypoxic tumor areas by utilizing the advantageous features of tri-modal magnetic resonance imaging (MRI). SPION@ND exhibits hypoxia-triggered dispersion-aggregation structural transformation. Dispersed SPION@ND can be used for routine clinical BTV construction using T1-contrast MRI. Conversely, aggregated SPION@ND can be used for tumor hypoxia imaging assessment using T2-contrast MRI. Moreover, by introducing T2 mapping, this work designs a novel method (adjustable threshold-based hypoxia assessment) for the precise assessment of tumor hypoxia confidence area and hypoxia level. Eventually this work successfully obtains hypoxia tumor target and accurates hypoxia tumor target, and achieves a one-stop hypoxia-guided BTV construction. Compared to the positron emission tomography-based hypoxia assessment, SPION@ND provides a new method that allows safe and convenient imaging of hypoxic tumor areas in clinical settings.

Multi-Stimuli-Responsive and Cell Membrane Camouflaged Aggregation-Induced Emission Nanogels for Precise Chemo-photothermal Synergistic Therapy of Tumors

Targeted and controllable drug release at lesion sites with the aid of visual navigation in real-time is of great significance for precise theranostics of cancers. Benefiting from the marvelous features (e.g., bright emission and phototheranostic effects in aggregates) of aggregation-induced emission (AIE) materials, constructing AIE-based multifunctional nanocarriers that act as all-arounders to integrate multimodalities for precise theranostics is highly desirable. Here, an intelligent nanoplatform (P-TN-Dox@CM) with homologous targeting, controllable drug release, and in vivo dual-modal imaging for precise chemo-photothermal synergistic therapy is proposed. AIE photothermic agent (TN) and anticancer drug (Dox) are encapsulated in thermo-/pH-responsive nanogels (PNA), and the tumor cell membranes are camouflaged onto the surface of nanogels. Active targeting can be realized through homologous effects derived from source tumor cell membranes, which advantageously elevates the specific drug delivery to tumor sites. After being engulfed into tumor cells, the nanogels exhibit a burst drug release at low pH. The near-infrared (NIR) photoinduced local hyperthermia can activate severe cytotoxicity and further accelerate drug release, thus generating enhanced synergistic chemo-photothermal therapy to thoroughly eradicate tumors. Moreover, P-TN-Dox@CM nanogels could achieve NIR-fluorescence/photothermal dual-modal imaging to monitor the dynamic distribution of therapeutics in real-time. This work highlights the great potential of smart P-TN-Dox@CM nanogels as a versatile nanoplatform to integrate multimodalities for precise chemo-photothermal synergistic therapy in combating cancers.

Recent Development of Rhenium-Based Materials in the Application of Diagnosis and Tumor Therapy

Rhenium (Re) is widely used in the diagnosis and treatment of cancer due to its unique physical and chemical properties. Re has more valence electrons in its outer shell, allowing it to exist in a variety of oxidation states and to form different geometric configurations with many different ligands. The luminescence properties, lipophilicity, and cytotoxicity of complexes can be adjusted by changing the ligand of Re. This article mainly reviews the development of radionuclide 188Re in radiotherapy and some innovative applications of Re as well as the different therapeutic approaches and imaging techniques used in cancer therapy. In addition, the current application and future challenges and opportunities of Re are also discussed.

Nano-Metal-Organic Framework Decorated With Pt Nanoparticles as an Efficient Theranostic Nanoprobe for CT/MRI/PAI Imaging-Guided Radio-Photothermal Synergistic Cancer Therapy

The multifunctional theranostic nanoplatforms, which can realize changing the contrasts of medical images and enhance cancer therapies simultaneously, have attracted tremendous attention from chemists and medicine in past decades. Herein, a nanoscale metal-organic framework-based material was first synthesized and then decorated with platinum (NMOF545@Pt) successfully for multimodal imaging-guided synergistic cancer therapy. The obtained NMOF545@Pt is advantageous in shortening the longitudinal relaxation time (T1), enhancing photoacoustic effects, and elevating X-ray absorption efficiently. Thus, the enchantments of tripe imaging modalities, computed tomography (CT)/magnetic resonance imaging (MRI)/photoacoustic imaging (PAI), were realized with NMOF545@Pt administration simultaneously and can be cleared from the mice. Meanwhile, in vitro and in vivo experiments demonstrate that the synthesized NMOF545@Pt can dramatically increase photothermal therapy (PTT) and radiotherapy (RT) efficacy. Convincing evidence proves that tumor growth can be wholly inhibited without noticeable side effects or organ damage. The results demonstrated the promise of multifunctional nanocomposites NMOF545@Pt to improve biomedical imaging and synergistic tumor treatments.

Dual-Mode Tumor Imaging Using Probes That Are Responsive to Hypoxia-Induced Pathological Conditions

Hypoxia in solid tumors is associated with poor prognosis, increased aggressiveness, and strong resistance to therapeutics, making accurate monitoring of hypoxia important. Several imaging modalities have been used to study hypoxia, but each modality has inherent limitations. The use of a second modality can compensate for the limitations and validate the results of any single imaging modality. In this review, we describe dual-mode imaging systems for the detection of hypoxia that have been reported since the start of the 21st century. First, we provide a brief overview of the hallmarks of hypoxia used for imaging and the imaging modalities used to detect hypoxia, including optical imaging, ultrasound imaging, photoacoustic imaging, single-photon emission tomography, X-ray computed tomography, positron emission tomography, Cerenkov radiation energy transfer imaging, magnetic resonance imaging, electron paramagnetic resonance imaging, magnetic particle imaging, and surface-enhanced Raman spectroscopy, and mass spectrometric imaging. These overviews are followed by examples of hypoxia-relevant imaging using a mixture of probes for complementary single-mode imaging techniques. Then, we describe dual-mode molecular switches that are responsive in multiple imaging modalities to at least one hypoxia-induced pathological change. Finally, we offer future perspectives toward dual-mode imaging of hypoxia and hypoxia-induced pathophysiological changes in tumor microenvironments.

Injectable Hydrogel Based on Defect-Rich Multi-Nanozymes for Diabetic Wound Healing via an Oxygen Self-Supplying Cascade Reaction

Diabetic wound healing remains challenging owing to the risk for bacterial infection, hypoxia, excessive glucose levels, and oxidative stress. Glucose-activated cascade reactions can consume glucose and eradicate bacteria, avoiding the direct use of hydrogen peroxide (H₂ O₂ ) and wound pH restriction on peroxidase-like activity. However, the anoxic microenvironment in diabetic wounds impedes the cascade reaction due to the oxygen (O₂ ) dependence of glucose oxidation. Herein, defect-rich molybdenum disulfide nanosheets loaded with bovine serum albumin-modified gold nanoparticle (MoS₂ @Au@BSA NSs) heterostructures are designed and anchored onto injectable hydrogels to promote diabetic wound healing through an O₂ self-supplying cascade reaction. BSA decoration decreases the particle size of Au, increasing the activity of multiple enzymes. Glucose oxidase-like Au catalyzes the oxidation of glucose into gluconic acid and H₂ O₂ , which is transformed into a hydroxyl radical (•OH) catalyzed by peroxidase-like MoS₂ @Au@BSA to eradicate bacteria. When the wound pH reaches an alkalescent condition, MoS₂ @Au@BSA mimicks superoxide dismutase to transform superoxide anions into O₂ and H₂ O₂ , and decomposes endogenous and exogenous H₂ O₂ into O₂ via catalase-like mechanisms, reducing oxidative stress, alleviating hypoxia, and facilitating glucose oxidation. The MoS₂ @Au@BSA nanozyme-anchored injectable hydrogel, composed of oxidized dextran and glycol chitosan crosslinked through a Schiff base, significantly accelerates diabetic wound healing.

Imaging methods to evaluate tumor microenvironment factors affecting nanoparticle drug delivery and antitumor response

Standard small molecule and nanoparticulate chemotherapies are used for cancer treatment; however, their effectiveness remains highly variable. One reason for this variable response is hypothesized to be due to nonspecific drug distribution and heterogeneity of the tumor microenvironment, which affect tumor delivery of the agents. Nanoparticle drugs have many theoretical advantages, but due to variability in tumor microenvironment (TME) factors, the overall drug delivery to tumors and associated antitumor response are low. The nanotechnology field would greatly benefit from a thorough analysis of the TME factors that create these physiological barriers to tumor delivery and treatment in preclinical models and in patients. Thus, there is a need to develop methods that can be used to reveal the content of the TME, determine how these TME factors affect drug delivery, and modulate TME factors to increase the tumor delivery and efficacy of nanoparticles. In this review, we will discuss TME factors involved in drug delivery, and how biomedical imaging tools can be used to evaluate tumor barriers and predict drug delivery to tumors and antitumor response.

Gold Nanoparticles in Cancer Theranostics

Conventional cancer treatments, such as surgical resection, radiotherapy, and chemotherapy, have achieved significant progress in cancer therapy. Nevertheless, some limitations (such as toxic side effects) are still existing for conventional therapies, which motivate efforts toward developing novel theranostic avenues. Owning many merits such as easy surface modification, unique optical properties, and high biocompatibility, gold nanoparticles (AuNPs and GNPs) have been engineered to serve as targeted delivery vehicles, molecular probes, sensors, and so on. Their small size and surface characteristics enable them to extravasate and access the tumor microenvironment (TME), which is a promising solution to realize highly effective treatments. Moreover, stimuli-responsive properties (respond to hypoxia and acidic pH) of nanoparticles to TME enable GNPs’ unrivaled control for effective transport of therapeutic cargos. In this review article, we primarily introduce the basic properties of GNPs, further discuss the recent progress in gold nanoparticles for cancer theranostics, with an additional concern about TME stimuli-responsive studies.

Functional CT Contrast Nanoagents for the Tumor Microenvironment

Understanding the detailed tumor microenvironment (TME) is essential to achieve effective treatment of tumor, because TME has an extremely profound influence on the occurrence, development, invasion, and metastasis of tumor. It is of great significance to realize accurate diagnosis of the TME by using functional computed tomography (CT) contrast nanoagents (FCTNAs). Here, an overview of FCTNAs that respond to the overexpressed receptors, acidic microenvironment, overexpressed glutathione and enzymes, and hypoxia in tumor is provided, and also prospects the advance of novel spectral CT technique to detect the TME precisely. Utilizing FCTNAs is expected to achieve accurate monitoring of the TME and further provide guidance for the effective personalized tumor treatment in clinic.

CT/NIRF dual-modal imaging tracking and therapeutic efficacy of transplanted mesenchymal stem cells labeled with Au nanoparticles in silica-induced pulmonary fibrosis

Mesenchymal stem cells (MSCs) have shown promising therapeutic effects in cell-based therapies and regenerative medicine. Efficient tracking of MSCs is an urgent clinical need that will help us to understand their behavior after transplantation and allow adjustment of therapeutic strategies. However, no clinically approved tracers are currently available, which limits the clinical translation of stem cell therapy. In this study, a nanoparticle (NP) for computed tomography (CT)/fluorescence dual-modal imaging, Au@Albumin@ICG@PLL (AA@ICG@PLL), was developed to track bone marrow-derived mesenchymal stem cells (BMSCs) that were administered intratracheally into mice with silica-induced pulmonary fibrosis, which facilitated understanding of the therapeutic effect and the possible molecular mechanism of stem cell therapy. The AuNPs were first formed in bovine serum albumin (BSA) solution and modified with indocyanine green (ICG), and subsequently coated with a poly-l-lysine (PLL) layer to enhance intracellular uptake and biocompatibility. BMSCs were labeled with AA@ICG@PLL NPs with high efficiency without an effect on biological function or therapeutic capacity. The injected AA@ICG@PLL-labeled BMSCs could be tracked via CT and near-infrared fluorescence (NIRF) imaging for up to 21 days after transplantation. Using these NPs, the molecular anti-inflammatory mechanism of transplanted BMSCs was revealed, which included the downregulation of proinflammatory cytokines, suppression of macrophage activation, and delay of the fibrosis process. This study suggests a promising role for imaging-guided MSC-based therapy for pulmonary fibrosis, such as idiopathic pulmonary fibrosis (IPF) and pneumoconiosis.

A minireview on multiparameter-activated nanodevices for cancer imaging and therapy

Tumor microenvironment (TME)-responsive nanodevices are essential tools for cancer imaging and therapy. Exploiting the advantages of molecular engineering, nanodevices are emerging for biomedical applications. In order to reach targeted cancer areas, activated nanodevices first respond to the TME and then serve as an actuator for sensing, imaging and therapy. Most nanodevices depend on a single parameter as an input for their downstream activation, potentially leading to inaccurate diagnostic results and poor therapeutic outcomes. However, in the TME, some biomarkers are cross-linked, and such correlated biomarkers are potentially useful for cancer imaging and theranostic applications. Based on this phenomenon, researchers have developed approaches for the construction of multiparameter-activated nanodevices (MANs) to improve accuracy. This minireview summarizes the recent advances in the development of MANs for cancer imaging including fluorescence imaging, photoacoustic (PA) imaging, magnetic resonance imaging (MRI) and computed tomography (CT) imaging, as well as cancer therapy including radiotherapy, chemotherapy, photoinduced therapy and immunotherapy. We highlight different approaches for improving the specificity and precision of cancer imaging and therapy. In the future, MANs will show promise for clinical work in multimodal diagnosis and therapeutics.

Hyperthermia Induced by Gold Nanoparticles and Visible Light Photothermy Combined with Chemotherapy to Tackle Doxorubicin Sensitive and Resistant Colorectal Tumor 3D Spheroids

Current cancer therapies are frequently ineffective and associated with severe side effects and with acquired cancer drug resistance. The development of effective therapies has been hampered by poor correlations between pre-clinical and clinical outcomes. Cancer cell-derived spheroids are three-dimensional (3D) structures that mimic layers of tumors in terms of oxygen and nutrient and drug resistance gradients. Gold nanoparticles (AuNP) are promising therapeutic agents which permit diminishing the emergence of secondary effects and increase therapeutic efficacy. In this work, 3D spheroids of Doxorubicin (Dox)-sensitive and -resistant colorectal carcinoma cell lines (HCT116 and HCT116-DoxR, respectively) were used to infer the potential of the combination of chemotherapy and Au-nanoparticle photothermy in the visible (green laser of 532 nm) to tackle drug resistance in cancer cells. Cell viability analysis of 3D tumor spheroids suggested that AuNPs induce cell death in the deeper layers of spheroids, further potentiated by laser irradiation. The penetration of Dox and earlier spheroid disaggregation is potentiated in combinatorial therapy with Dox, AuNP functionalized with polyethylene glycol (AuNP@PEG) and irradiation. The time point of Dox administration and irradiation showed to be important for spheroids destabilization. In HCT116-sensitive spheroids, pre-irradiation induced earlier disintegration of the 3D structure, while in HCT116 Dox-resistant spheroids, the loss of spheroid stability occurred almost instantly in post-irradiated spheroids, even with lower Dox concentrations. These results point towards the application of new strategies for cancer therapeutics, reducing side effects and resistance acquisition.

Biomineralization-inspired nanozyme for single-wavelength laser activated photothermal-photodynamic synergistic treatment against hypoxic tumors

Hypoxia, one of the features of most solid tumors, can severely impede the efficiency of oxygen-dependent treatments such as chemotherapy, radiotherapy and type-II photodynamic therapy. Herein, a catalase-like nanozyme RuO₂@BSA (RB) was first prepared through a biomineralization strategy, and a high efficiency near-infrared photosensitizer (IR-808-Br₂) was further loaded into the protein shell to generate the safe and versatile RuO₂@BSA@IR-808-Br₂ (RBIR) for the imaging-guided enhanced phototherapy against hypoxic tumors. RB not only acts like a catalase, but also serves as a photothermal agent that speeds up the oxygen supply under near-infrared irradiation (808 nm). The loaded NIR photosensitizer could immediately convert molecular oxygen (O₂) to cytotoxic singlet oxygen (¹O₂) upon the same laser irradiation. Results indicated that RBIR achieved enhanced therapeutic outcomes with negligible side effects. Features such as a simple synthetic route and imaging-guided and single-wavelength-excited phototherapy make the nanozyme a promising agent for clinical applications.

Long-term in vivo CT tracking of mesenchymal stem cells labeled with Au@BSA@PLL nanotracers

Human mesenchymal stem cells (hMSCs) transplantation has attracted considerable interest for the treatment of pulmonary injury. Noninvasive and long-term tracking of hMSCs after transplantation in vivo, which is important for our understanding of the stem cell therapy, still remains a big challenge. Herein, we report on the development of a novel gold nanoparticle-based nanotracer to track by CT imaging the transplantation of hMSCs in vivo. Gold nanoparticles (AuNPs) were synthesized on bovine serum albumin (BSA) via an in situ growth method and modified with a poly-l-lysine (PLL) layer, yielding Au@BSA@PLL nanotracers with enhanced biocompatibility and intracellular uptake. Au@BSA@PLL nanotracers were explored for in vitro and in vivo tracking of hMSCs with computer tomography (CT). Our results showed that the endocytosis of Au@BSA@PLL by hMSCs was as high as ∼293 pg per cell. Meanwhile, the nanotracers had a negligible influence on the viability, proliferation, and osteogenic and adipogenic differentiation of the labeled hMSCs. Using a pulmonary fibrosis injury mouse model induced by bleomycin, the labeled hMSCs could be tracked by CT imaging up to 23 d after transplanted in vivo, suggesting the feasibility of Au@BSA@PLL as a potential cellular nanotracer for noninvasive and long-term CT tracking of hMSCs in lung tissue repair.

Nanotheranostics Targeting the Tumor Microenvironment

Cancer is considered the most aggressive malignancy to humans, and definitely the major cause of death worldwide. Despite the different and heterogenous presentation of the disease, there are pivotal cell elements involved in proliferation, differentiation, and immortalization, and ultimately the capability to evade treatment strategies. This is of utmost relevance when we are just beginning to grasp the complexity of the tumor environment and the molecular "evolution" within. The tumor micro-environment (TME) is thought to provide for differentiation niches for clonal development that results in tremendous cancer heterogeneity. To date, conventional cancer therapeutic strategies against cancer are failing to tackle the intricate interplay of actors within the TME. Nanomedicine has been proposing innovative strategies to tackle this TME and the cancer cells that simultaneously provide for biodistribution and/or assessment of action. These nanotheranostics systems are usually multi-functional nanosystems capable to carry and deliver active cargo to the site of interest and provide diagnostics capability, enabling early detection, and destruction of cancer cells in a more selective way. Some of the most promising multifunctional nanosystems are based on gold nanoparticles, whose physic-chemical properties have prompt for the development of multifunctional, responsive nanomedicines suitable for combinatory therapy and theranostics. Herein, we shall focus on the recent developments relying on the properties of gold nanoparticles as the basis for nanotheranostics systems against the heterogeneity within the TME.

Seeing Better and Going Deeper in Cancer Nanotheranostics

Biomedical imaging modalities in clinical practice have revolutionized oncology for several decades. State-of-the-art biomedical techniques allow visualizing both normal physiological and pathological architectures of the human body. The use of nanoparticles (NP) as contrast agents enabled visualization of refined contrast images with superior resolution, which assists clinicians in more accurate diagnoses and in planning appropriate therapy. These desirable features are due to the ability of NPs to carry high payloads (contrast agents or drugs), increased in vivo half-life, and disease-specific accumulation. We review the various NP-based interventions for treatments of deep-seated tumors, involving "seeing better" to precisely visualize early diagnosis and "going deeper" to activate selective therapeutics in situ.

Biological reduction of nitroimidazole-functionalized gold nanorods for photoacoustic imaging of tumor hypoxia

Tumor-selective accumulation of gold nanorods (GNR) has been demonstrated for visualization of tumor hypoxia by photoacoustic imaging. We prepared GNRs with hypoxia-targeting nitroimidazole units (G-NI) on their surface. Biological experiments revealed that G-NI produced a strong photoacoustic signal in hypoxic tumor cells and tissues.

Tumor-selective accumulation of gold nanorods (GNR) has been demonstrated for visualization of tumor hypoxia by photoacoustic imaging.

Breaking the Depth Dependence by Nanotechnology-Enhanced X-Ray-Excited Deep Cancer Theranostics

The advancements in nanotechnology have created multifunctional nanomaterials aimed at enhancing diagnostic accuracy and treatment efficacy for cancer. However, the ability to target deep-seated tumors remains one of the most critical challenges for certain nanomedicine applications. To this end, X-ray-excited theranostic techniques provide a means of overcoming the limits of light penetration and tissue attenuation. Herein, a comprehensive overview of the recent advances in nanotechnology-enhanced X-ray-excited imaging and therapeutic methodologies is presented, with an emphasis on the design of multifunctional nanomaterials for contrast-enhanced computed tomography (CT) imaging, X-ray-excited optical luminescence (XEOL) imaging, and X-ray-excited multimodal synchronous/synergistic therapy. The latter is based on the concurrent use of radiotherapy with chemotherapy, gas therapy, photodynamic therapy, or immunotherapy. Moreover, the featured biomedical applications of X-ray-excited deep theranostics are discussed to highlight the advantages of X-ray in high-sensitivity detection and efficient elimination of malignant tumors. Finally, key issues and technical challenges associated with this deep theranostic technology are identified, with the intention of advancing its translation into the clinic.

Recent advances in nanomaterial-based synergistic combination cancer immunotherapy

This review aims to summarize various synergistic combination cancer immunotherapy strategies based on nanomaterials.

A versatile probe for serum albumin and its application for monitoring wounds in live zebrafish

A versatile probe for serum albumin and its application in monitoring wounds in live zebrafish.

Targeted tumor dual mode CT/MR imaging using multifunctional polyethylenimine-entrapped gold nanoparticles loaded with gadolinium

We report the construction and characterization of polyethylenimine (PEI)-entrapped gold nanoparticles (AuNPs) chelated with gadolinium (Gd) ions for targeted dual mode tumor CT/MR imaging in vivo. In this work, polyethylene glycol (PEG) monomethyl ether-modified PEI was sequentially modified with Gd chelator and folic acid (FA)-linked PEG (FA-PEG) was used as a template to synthesize AuNPs, followed by Gd(III) chelation and acetylation of the remaining PEI surface amines. The formed FA-targeted PEI-entrapped AuNPs loaded with Gd (FA-Gd-Au PENPs) were well characterized in terms of structure, composition, morphology, and size distribution. We show that the FA-Gd-Au PENPs with an Au core size of 3.0 nm are water dispersible, colloidally stable, and noncytotoxic in a given concentration range. Thanks to the coexistence of Au and Gd elements within one nanoparticulate system, the FA-Gd-Au PENPs display a better X-ray attenuation property than clinical iodinated contrast agent (e.g. Omnipaque) and reasonable r1 relaxivity (1.1 mM-1s-1). These properties allow the FA-targeted particles to be used as an efficient nanoprobe for dual mode CT/MR imaging of tumors with excellent FA-mediated targeting specificity. With the demonstrated organ biocompatibility, the designed FA-Gd-Au PENPs may hold a great promise to be used as a nanoprobe for CT/MR dual mode imaging of different FA receptor-overexpressing tumors.

Contrast-enhanced computed tomography combined with Chitosan-Fe3O4 nanoparticles targeting fibroblast growth factor receptor and vascular endothelial growth factor receptor in the screening of early esophageal cancer

Esophageal cancer is a malignant tumor with a relatively high invasiveness, metastatic potential and worldwide incidence among human cancers. The majority of patients with esophageal cancer are diagnosed in a late tumor stage due to a lack of advanced and sensitive protocols for the diagnosis of patients with early-stage esophageal cancer. In the current study, contrast-enhanced computerized tomography (CECT) combined with Chitosan-Fe₃O₄ nanoparticles targeting fibroblast growth factor receptor (FGFR) and vascular endothelial growth factor receptor (VEGFR; CECT-CNFV) were used to diagnose patients with suspected esophageal cancer. A Chitosan-Fe₃O₄-parceled bispecific antibody targeting FGFR and VEGFR was produced and its affinity to esophageal cancer cells was determined both in vitro and in vivo. A total of 320 patients with suspected esophageal cancer were voluntarily recruited to evaluate the efficacy of CECT-CNFV in the diagnosis of early-stage esophageal cancer. All participants were subjected to CT and CECT-CNFV to detect whether tumors were present in the esophageal area. A Chitosan-Fe₃O₄ nanoparticles contrast agent was orally administered at 20 min prior to CT and CECT-CNFV. The results demonstrated that CECT-CNFV improved diagnostic sensitivity and provided a novel protocol for the diagnosis of tumors in patients with suspected gastric cancer at an early-stage. Furthermore, the resolution ratio of images was enhanced by CECT-CNFV, which enabled the visualization of tiny tumor nodules in esophageal tissue. Clinical data demonstrated that CECT-CNFV diagnosed 200 patients with suspected early-stage esophageal cancer and 120 patients as tumor free. In addition, CECT-CNFV exhibited higher signal enhancement of tumor nodules than CT, suggesting a higher accuracy and accumulation of nanoparticle contrast agent within the tumor nodules of esophageal tissue. Notably, the survival rate of patients with esophageal cancer diagnosed at an early-stage by CECT-CNFV was higher than the mean five-year survival rate (P<0.01). In conclusion, CECT-CNFV enhanced the sensitivity and accuracy of CT in the diagnosis of early-stage esophageal cancer. Thus, CECT-CNFV may improve the accuracy of CT in the diagnosis of mural enhancement in patients with esophageal cancer.

Selective cancer treatment via photodynamic sensitization of hypoxia-responsive drug delivery

The precise and selective delivery of chemodrugs into tumors represents a critical requirement for anti-cancer therapy. Intelligent delivery systems that are responsive to a single internal or external stimulus often lack sufficient cancer selectivity, which compromises the drug efficacy and induces undesired side effects. To overcome this dilemma, we herein report a cancer-targeting vehicle which allows highly cancer-selective drug release in response to cascaded external (light) and internal (hypoxia) dual triggers. In particular, doxorubicin (DOX)-loaded, hypoxia-dissociable nanoparticles (NPs) were prepared from self-assembled polyethylenimine-nitroimidazole (PEI-NI) micelles that were further co-assembled with hyaluronic acid-Ce6 (HC). Upon accumulation in tumor cells, tumor site-specific light irradiation (660 nm, 10 mW cm^-2) generated high levels of reactive oxygen species (ROS) and greatly enhanced the hypoxic levels to induce NP dissociation and accordingly DOX release. A synergistic anti-cancer efficacy between DOX-mediated chemotherapy and Ce6-mediated photodynamic therapy (PDT) was thus achieved, resulting in reduced side effects to normal tissues/cells. This study therefore provides an effective method to control the cancer-specific drug delivery by responding to cascaded multiple triggers, and it renders promising applications for the programmed combination of chemotherapy and PDT toward cancer treatment.

The functionalization of natural polymer-coated gold nanoparticles to carry bFGF to promote tissue regeneration

A schematic of the preparation of natural polymer-coated AuNPs for monitoring tissue regeneration stimulated by bFGF.

Application of novel targeting nanoparticles contrast agent combined with contrast-enhanced computed tomography during screening for early-phase gastric carcinoma

Gastric cancer is one of the most common human tumors worldwide. The biggest bottleneck is a lack of advanced and sensitive protocols for the diagnosis of patients with early-stage gastric cancer. Therefore, more sensitive methods of diagnosing gastric cancer are urgently required to improve survival rates. In this clinical study, contrast-enhanced computed tomography (CECT) with targeting nanoparticles contrast agent (CECT-TNCA) was used to diagnose early-stage gastric cancer. The specific-targeted tyrosine kinase inhibitors of gastric cancer, including platelet-derived growth factor receptor-β, Ret and Kit, were used as TNCAs. A total of 484 patients with suspected gastric cancer were voluntarily recruited to investigate the efficacy of CECT-TNCA in the diagnosis of patients with early-stage gastric cancer. Patients with suspected gastric cancer were subjected CT and CECT-TNCA to detect whether gastric tumors existed. TNCA was orally administered before CT and CECT-TNCA (20 min). Our diagnostic data revealed that CECT-TNCA improved sensitivity and provided a new protocol to diagnose tumors in patients with suspected gastric cancer at the early stage. In addition, imaging using CECT-TNCA enabled the visualization of tiny nodules in the gastric area. CECT-TNCA diagnosed 182 patients with suspected gastric cancer as tumor-free. CECT-TNCA confirmed gastric cancer in 302 patients. Our novel diagnosis indicated significantly (P<0.01) differential signal enhancement in the gastric nodules via CECT-TNCA compared with CT, suggesting higher accuracy and the accumulation of TNCA in tumor nodules in the stomach. Furthermore, survival rates of patients detected by early-diagnosis of CECT-TNCA were significantly higher than the mean five-year survival (P<0.01). In conclusion, our investigations demonstrate that the sensibility and accuracy of CT is improved through combination with liposome-encapsulated nanoparticle contrast agent for the diagnosis of early stage gastric cancer when compared with single CT detection. CECT-TNCA improves the accuracy of CT and diagnostic confidence in assessing mural enhancement in patients with suspected gastric cancer.

Strategies for Preparing Albumin-based Nanoparticles for Multifunctional Bioimaging and Drug Delivery

Biosafety is the primary concern in clinical translation of nanomedicine. As an intrinsic ingredient of human blood without immunogenicity and encouraged by its successful clinical application in Abraxane, albumin has been regarded as a promising material to produce nanoparticles for bioimaging and drug delivery. The strategies for synthesizing albumin-based nanoparticles could be generally categorized into five classes: template, nanocarrier, scaffold, stabilizer and albumin-polymer conjugate. This review introduces approaches utilizing albumin in the preparation of nanoparticles and thereby provides scientists with knowledge of goal-driven design on albumin-based nanomedicine.

Surfactant-Free Aqueous Synthesis of Novel Ba2GdF7:Yb3+, Er3+@PEG Upconversion Nanoparticles for in Vivo Trimodality Imaging

In this work, we developed the surfactant-free aqueous synthesis of novel polyethylene glycol (PEG) coated Ba₂GdF₇:Yb³⁺, Er³⁺ upconversion nanoparticles (named as, Ba₂GdF₇:Yb³⁺, Er³⁺@PEG UCNPs) for in vivo multimodality imaging including upconversion luminescence (UCL), X-ray computed tomography (CT), and T₁-weighted magnetic resonance (MR). The as-prepared Ba₂GdF₇:Yb³⁺, Er³⁺@PEG UCNPs not only present bright UCL and reasonably high CT/MR enhancements but also exhibit excellent colloidal stability, inappreciable cytotoxicity, and negligible organ toxicity. In particular, the Ba₂GdF₇:Yb³⁺, Er³⁺@PEG UCNPs emit red UCL with high intensity in the tumor site after intravenous injection via the tail vein of a nude mouse. The Ba₂GdF₇:Yb³⁺, Er³⁺@PEG UCNPs as contrast agents exhibit high-performance for in vivo trimodality (UCL/CT/MR) imaging of a tumor during HepG2 tumor-bearing nude mouse experiments.

A biomimetic Au@BSA-DTA nanocomposites-based contrast agent for computed tomography imaging

Early detection of cancer is increasingly important for being considered to increase the survival rate in the treatment process. The past decades years have witnessed the great progress in the biological detection application of gold nanoparticles. Herein, we reported a facile one-pot synthesis process to obtain gold nanoparticles (Au@BSA) with bovine serum albumin (BSA) as a biotemplate following with conjugation of diatrizoic acid (DTA) for a potential X-ray computed tomography (CT) imaging contrast agent (Au@BSA-DTA). The as-prepared biomimetic material was characterized systematically by several techniques. It was shown that the prepared biomaterial is colloid stable under the tested range of pH and temperature. The cell cytotoxicity assay, hemolytic assay and cell morphology observation showed that Au@BSA-DTA has good biocompatibility and hemocompatibility at a concentration of Au even up to 80μg/mL. Besides, the biomimetic material Au@BSA-DTA with double radiodense elements of Au and iodine displayed much stronger CT imaging effect compared with the traditional small molecule contrast agents, which paves the potential clinical application in cancer early diagnosis.

Renal Clearable Ag Nanodots for in Vivo Computer Tomography Imaging and Photothermal Therapy

Albumin-stabilized Ag nanodots (ANDs) are prepared by a one-step biomineralization method. The highly crystallized nanodots have ultrasmall sizes (approximately 5.8 nm) and robust X-ray attenuation (5.7313 HU per mM Ag). The unlabeled ANDs are directly excreted from the body via the urine after in vivo X-ray computer tomography (CT) imaging application. ANDs could be used as CT imaging agents and effective photothermal therapy agents. Tumor growth inhibition reaches 90.2% after photothermal treatment with ANDs. ANDs are promising tools for in vivo CT imaging and clearable near-infrared-triggered theranostic agents.